1. Field of Invention
The invention relates to an optical element supporting plate for a scanner unit that scans and irradiates light generated by a light source, more particularly, to an optical element supporting plate that fixes an optical element, that provides an optical path of the light, in a housing of the scanner unit.
2. Description of Related Art
A conventional scanner unit includes various optical elements in its housing, such as lenses, mirrors, slit plates and a polygon mirror, which deflect light generated by a light source, such as a laser emitting portion, in a predetermined scanning direction. These optical elements are fixed to the housing, using an adhesive, screws, or other fixative means, to support one end face of the optical elements at a bottom portion of the housing while the other end face of the optical elements are urged toward the screws using springs.
However, when the optical elements are fixed to the housing using an adhesive, the location and/or angle of the optical elements might change if the scanner unit is subjected to shocks and/or vibrations before the adhesive sets. Therefore, it is undesirable to use an adhesive at portions requiring mounting accuracy. When the optical elements are fixed to the housing using screws and springs, the screws must have sufficient strength so as to securely support the optical element in a proper position against the urging force from the springs.
The invention provides an optical element supporting plate for a relatively small-sized scanner unit, which can stably secure an optical element in a proper position.
According to one aspect of the invention, a supporting plate for an optical element used in a scanner unit that scans and irradiates light includes an engagement portion to be attached to a supporting member projected from a housing of the scanner unit, and a spring portion bent from the engagement portion toward the supporting member. The spring portion exerts an urging force toward the supporting member on an optical element disposed between the supporting member and the spring portion.
According to the invention, the engagement portion of the supporting plate engages the supporting member. The one end face of the optical element is supported by the supporting member, and the other end face of the optical element is urged toward the engagement portion by a spring portion of the supporting plate. Consequently, the optical element can be secured in the proper position with stability.